The effect of hinge position on corneal sensation and dry eye after LASIK

Comparative study of dry eye after Phacoemulsification in senile cataract

“…18,19 The disruption in corneal sensitivity due to the incisions in clear cornea phacoemulsification, although small, could lead to decrease in tear production similar to that found in LASIK. The sub-basal nerve encounters the cornea from the limbal side, mainly from the temporal and nasal quadrants, and then divides toward the central area.…”

Cataract Surgery and Dry Eye

“…It is estimated that there are approximately 7000 sensory receptors per square millimeter in the human corneal epithelium, implying that injuries to individual epithelial cells may be adequate to give a sensation (Muller et al, 2003). Traditionally, it was believed that most sensory nerves enter into the cornea along a transverse meridian (3-and 9-o'clock); this was in accordance with the clinical findings of better corneal sensation and less dry eye symptoms in patients undergoing laser in situ keratomileusis (LASIK) with a nasal hinge (Donnenfeld et al, 2003;Kohlhaas, 1998;Lee and Joo, 2003). However, the current description is that nerve bundles enter the peripheral mid-stromal cornea in a radial fashion, along different meridians and parallel to the corneal surface.…”

“…This is one of the major pathogenic pathways in induction of postoperative dry eye in patients undergoing ophthalmic surgeries. Most surgical procedures that cause denervation of the cornea result in impaired epithelial wound healing, increased epithelial permeability, decreased epithelial metabolic activity and loss of cytoskeletal structures associated with cellular adhesion (Donnenfeld et al, 2003;Kohlhaas, 1998). As mentioned earlier, the normal corneal epithelium has the highest density of sensory nerve endings throughout the human body.…”

“…Until now, at least 17 different neuropeptides and neurotransmitters have been described in the corneal nerves (Dastjerdi and Dana, 2009). There are evidences that intact corneal nerve fibers exert trophic influences on the corneal epithelium and neuroregulation is responsible for maintenance of the integrity and repair of the ocular surface (Donnenfeld et al, 2003). The mechanism underlying corneal damage in patients with reduced corneal sensation and dry eye -for instance, following surgery -is thought to be related to reduced levels of neurotransmitters.…”

Ön Segment Cerrahileri ve Kuru Göz; Tanı ve Tedavi Yaklaşımı

“…Yapılan diğer çalışmalar, femtosaniye laser ile uygulanan LASIK'te superior menteşe veya nazal/temporal menteşe pozisyonunun kornea duyarlılığına veya kuru göz parametrelerine etkisi olmadığını göstermiştir. 59 Rodriquez ve ark. 58 femtosaniye laser (34 göz, cerrahi öncesi sferik eşdeğer -3,1±3,1 D) ve manuel mikrokeratom (30 göz, cerrahi öncesi sferik eşdeğer -2,0±3,8 D) ile yapılan LASIK olgularını karşılaştırmış ve tüm olgularda LASIK sonrası 6. aydan sonra düzelen goblet hücre kaybını göstermiştir.…”